We shall continue work, as outlined in our original application, trying to define various tumor associated antigens in chemically induced mouse sarcomas, including tumor specific transplantation antigens that are essentially unique for each sarcoma, possibly occurring sarcoma-specific antigens shared by most or all sarcomas, as well as various differentiation antigens. The involvement of antigens of MuLV will, as in the past, be checked for as well. Serological methods will be primarily used, coupled with transplantation assays as needed. The Milstein-Kohler hybridoma technique will be the method of choice for most of our experiments.